ffffiirrss..iinndddd vvii 1144//0033//1122 55::3355 PPMM Cyber Forensics ffffiirrss..iinndddd ii 1144//0033//1122 55::3355 PPMM Founded in 1807, John Wiley & Sons is the oldest independent publishing company in the United States. With offi ces in North America, Europe, Asia, and Australia, Wiley is globally committed to developing and marketing print and electronic products and services for our customers’ professional and personal knowledge and understanding. The Wiley Corporate F&A series provides information, tools, and insights to corporate professionals responsible for issues affecting the profi tability of their company, from accounting and fi nance to internal controls and performance management. ffffiirrss..iinndddd iiii 1144//0033//1122 55::3355 PPMM Cyber Forensics From Data to Digital Evidence ALBERT J. MARCELLA, JR., PhD, CISA, CISM FREDERIC GUILLOSSOU, CISSP, CCE John Wiley & Sons, Inc. ffffiirrss..iinndddd iiiiii 1144//0033//1122 55::3355 PPMM Copyright © 2012 by John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authoriza- tion through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 646-8600, or on the Web at www.copyright.com. 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ISBN 978-1-118-27366-1 (hardback); ISBN 978-1-118-28268-7 (ebk); ISBN 978-1-118-28505-3 (ebk); ISBN 978-1-118-28731-6 (ebk) 1. Forensic sciences—Technological innovations. 2. Electronic evidence. 3. Evidence, Criminal. 4. Criminal investigation. 5. Computer crimes— Investigation. I. Guillossou, Frederic, 1970 - II. Title. HV8073.5.M168 2012 363.250285—dc23 2011048568 Printed in the United States of America 10 9 8 7 6 5 4 3 2 1 ffffiirrss..iinndddd iivv 1144//0033//1122 55::3355 PPMM Al Marcella To my wife Diane . . . . A sunbeam to warm you, A moonbeam to charm you, A sheltering angel, so nothing can harm you. May you always know how happy you make me, and how much I love you! Love doesn’t make the world go round; love is what makes the ride worthwhile. Thank you for sharing with me, the ride of a lifetime. ∞ + 1 Fredric Guillossou To my wife and daughter Alexandra and Nathalie The happy memories of the past, the joyful moments of the present, and the hope and promise of the future. ffffiirrss..iinndddd vv 1144//0033//1122 55::3355 PPMM ffffiirrss..iinndddd vvii 1144//0033//1122 55::3355 PPMM Contents Preface xiii Acknowledgments xvii Chapter 1: The Fundamentals of Data 1 Base 2 Numbering System: Binary and Character Encoding 2 Communication in a Two-State Universe 3 Electricity and Magnetism 3 Building Blocks: The Origins of Data 4 Growing the Building Blocks of Data 5 Moving Beyond Base 2 7 American Standard Code for Information Interchange 7 Character Codes: The Basis for Processing Textual Data 10 Extended ASCII and Unicode 10 Summary 12 Notes 13 Chapter 2: Binary to Decimal 15 American Standard Code for Information Interchange 16 Computer as a Calculator 16 Why Is This Important in Forensics? 18 Data Representation 18 Converting Binary to Decimal 19 Conversion Analysis 20 A Forensic Case Example: An Application of the Math 20 Decimal to Binary: Recap for Review 22 Summary 23 Chapter 3: The Power of HEX: Finding Slivers of Data 25 What the HEX? 26 Bits and Bytes and Nibbles 27 vii ffttoocc..iinndddd vviiii 1144//0033//1122 88::0011 AAMM viii (cid:2) Contents Nibbles and Bits 29 Binary to HEX Conversion 30 Binary (HEX) Editor 34 The Needle within the Haystack 39 Summary 41 Notes 42 Chapter 4: Files 43 Opening 44 Files, File Structures, and File Formats 44 File Extensions 45 Changing a File’s Extension to Evade Detection 47 Files and the HEX Editor 53 File Signature 55 ASCII Is Not Text or HEX 57 Value of File Signatures 58 Complex Files: Compound, Compressed, and Encrypted Files 59 Why Do Compound Files Exist? 60 Compressed Files 61 Forensics and Encrypted Files 64 The Structure of Ciphers 65 Summary 66 Notes 67 Appendix 4A: Common File Extensions 68 Appendix 4B: File Signature Database 73 Appendix 4C: Magic Number Defi nition 77 Appendix 4D: Compound Document Header 79 Chapter 5: The Boot Process and the Master Boot Record (MBR) 85 Booting Up 87 Primary Functions of the Boot Process 87 Forensic Imaging and Evidence Collection 90 Summarizing the BIOS 92 BIOS Setup Utility: Step by Step 92 The Master Boot Record (MBR) 96 Partition Table 102 Hard Disk Partition 103 Summary 110 Notes 111 ffttoocc..iinndddd vviiiiii 1144//0033//1122 88::0011 AAMM